To develop methods which will contribute to a reduction of breast cancer mortality, a Breast Self-Examination (BSE) education program which enlists social influences will be implemented and evaluated in whole communities. Levels of BSE frequency, quality, and proficiency will be raised in the entire population of women 20 years of older in these communities, and maintenance of these changes will be supported over a two year period, through a combination of intensive group education programs, broad participation, explicit attention to maintenance of the new behaviors, and use of educational methods of social influence. Our complete program will include group meetings arranged through natural social units, which will provide BSE skills and development of norms supportive of sustained practice; personal cuing materials; mass media messates for women in the target group and supportive others; physician encouragement; and brief repeat meetings after one year. Four matched communities will be selected from a pool of six after an initial telephone survey establishes current levels of BSE practice. One randomly allocated community will receive a two year program; a second will receive a one year program; a third will serve as a full-measurement control; and the fourth community will be a reduced measurement control. Through use of a variety of forms of the instructional program, tested recruitment techniques, and sponsorship of a community health agency, abouth 75% of the eligible women will receive person-to-person instruction in BSE techniques. Two annual follow-ups of the panels will combine phone and personal interviews. Measurement of BSE behaviors will combined detailed self-reports of frequency and quality, and tests of proficiency using breast models.